The long-range goal of the proposed research is to provide a thorough understanding of the complex regulation of hormone secretion by the adenohypophysis. Emphasis is placed on studies designed to elucidate the chemical nature and physiological significance of the hypothalamic releasing and inhibiting factors. Specifically, further attempts to isolate a separate FRF and an LRF distinct from the decapeptide will be performed. Concurrently, attempts to isolate GRF and PIF will be made. Studies on the mechanism of release of these releasing factors from the hypothalamus and their mechanism of action at the pituitary cellular level will be continued. Attempts will be made to clarify the role of monoamines in adenohypophysial hormone secretion. Studies on the role of prostaglandins in the release of pituitary hormones by an action both at the hypothalamic and pituitary level are being actively pursued. Further studies of the influence of gonadal steroids on the responsiveness of the pituitary to LRF will be conducted. Lastly, a number of additional studies designed to elucidate further the regulation of pituitary hormone secretion are planned.